It is well known that generally a prior art rollover judgment apparatus judges whether a vehicle will roll over when a total of the rotational energy and potential energy of the vehicle exceeds rollover critical energy. This relation can be expressed as the rollover critical curve of an ω (i.e., a roll angular velocity)−θ (i.e., a roll angle) map.
Such a prior art rollover judgment apparatus is so constructed as to deploy a curtain air bag in order to prevent any passenger from directly colliding with a side window and a pillar member when a rollover occurs in the vehicle and to prevent any passenger from bursting out of the vehicle to get injured. Therefore, it is necessary to deploy the curtain air bag in the gap between the side window and any passenger (for example, refer to patent references 1 and 2).
[Patent reference 1] JP,2001-71844,A
[Patent reference 2] JP,2001-71787,A
However, in accordance with the energy judgment method as disclosed in the above-mentioned patent application publications, although judgment of whether the vehicle will roll over can be implemented, it is difficult to implement prediction of a passenger's amount of movement which is caused by the inclination and lateral direction acceleration of the vehicle. A problem is therefore that there can be a case in which according to the time when the judgment is carried out, the tip part (or the lower part) of the curtain air bag is caught in a passenger's head or shoulder after the curtain air bag starts developing, and therefore it does not deploy normally and the purpose of protecting passengers cannot be accomplished.
The present invention is made in order to solve the above-mentioned problem, and it is therefore an object of the present invention to provide a rollover judgment apparatus which adds a rollover prediction function to judgment of an ω−θ map so as to judge a possibility which the vehicle will roll over at an early time.